Non-linear solid-state devices that control electrical conduction, such as diodes and transistors, marked the emergence of modern electronics. Counterpart devices for heat conduction would have important implications for thermal circuits, thermal management, and the field of phononics in general. Linear nanostructures have very high intrinsic thermal conductance, but they normally display no thermal rectification effects, i.e., they conduct heat along the central linear axis equally well in both directions. In recent years, theoretical proposals for thermal rectifiers have been put forward, but these involve complex coupling between individual atoms and substrates, which are difficult to construct as actual devices.
Asymmetric thermal conduction has been achieved by using a mechanical switch, but this “brute force” method is impractical for most applications. It would be highly desirable to have a simple, solid state, asymmetric thermal conduction device as the thermal analog of the solid state electrical diode.